improve linux-ssh-operator-skill: bug fixes, rsync support, tunneling docs

- Fix dry-run bug in ssh_alias_setup.sh (pub key check skipped when key was never generated)
- Remove dead code in ssh_run.sh (-- check after host arg was never reachable)
- Add --rsync/--delete flags to ssh_copy.sh for incremental rsync transfers
- Add -C/--compress flag to ssh_run.sh for slow-link connections
- Expand SKILL.md/SKILL.zh-CN.md: tunneling, jump host, SSH multiplexing, Docker ops
- Expand ssh-playbook.md: port forwarding, bastion, ControlMaster, structured troubleshooting table

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

linux-ssh-operator-skill/scripts/ssh_run.sh

@@ -14,6 +14,7 @@ Options:
   -p, --port PORT              SSH port (default: REMOTE_PORT or 22)
   -i, --key PATH               Identity file (default: REMOTE_KEY)
   -t, --tty                    Force pseudo-tty allocation (useful for sudo prompts)
+  -C, --compress               Enable SSH compression (useful on slow links)
       --accept-new             Set StrictHostKeyChecking=accept-new
       --sudo                   Prefix command with sudo --
       --sudo-non-interactive   Prefix command with sudo -n -- (fails if password needed)
@@ -36,6 +37,7 @@ key="${REMOTE_KEY:-}"
 connect_timeout="${REMOTE_CONNECT_TIMEOUT:-10}"
 
 tty=false
+compress=false
 accept_new=false
 sudo_mode=""
 dry_run=false
@@ -58,6 +60,10 @@ while [[ $# -gt 0 ]]; do
       tty=true
       shift
       ;;
+    -C|--compress)
+      compress=true
+      shift
+      ;;
     --accept-new)
       accept_new=true
       shift
@@ -126,14 +132,15 @@ if $accept_new; then
   ssh_opts+=(-o "StrictHostKeyChecking=accept-new")
 fi
 
+if $compress; then
+  ssh_opts+=(-C)
+fi
+
 if $tty; then
   ssh_opts+=(-tt)
 fi
 
 cmd=("$@")
-if [[ ${#cmd[@]} -gt 0 && "${cmd[0]}" == "--" ]]; then
-  cmd=("${cmd[@]:1}")
-fi
 if [[ -n "$sudo_mode" && ${#cmd[@]} -gt 0 ]]; then
   if [[ "$sudo_mode" == "sudo-n" ]]; then
     cmd=("sudo" "-n" "--" "${cmd[@]}")